1. Field of the Invention
The disclosures herein relate to an image forming method, and image forming apparatus, a non-transitory recording medium storing a program suitable for carrying out inkjet printing. The inkjet printing includes ejecting plural color liquid ink particles on a recording material so as to form a predetermined character or an image.
2. Description of the Related Art
Printers employing an inkjet system (hereinafter “inkjet printers”) generally produce high quality and inexpensive color printed matter. Hence, an increasing number of the inkjet printers is widely used not only in offices but is also used by general users along with the widespread use of personal computers or digital cameras.
In such inkjet printers, nozzles of recording heads discharge (eject) liquid ink particles in dots while a movable body (i.e., a carriage) integrally having ink cartridges and the recording heads reciprocate on a printing medium (i.e., a sheet) in directions orthogonal to a paper feeding direction. As a result, a predetermined character or an image is formed on a printing medium to produce desired printed matter. Further, since the carriage includes ink cartridges of four colors including black (K), yellow (Y), magenta (M), and cyan (C), and the recording heads of the respective colors, the inkjet printers not only perform monochrome printing but also carry out full color printing easily by combining these different colors (in practice, with additional colors such as light cyan and light magenta, six color cartridges, even color cartridges or eight color cartridges are used).
Further, in the above inkjet printers (generally called “multipath printers”) configured to perform printing while causing the recording heads disposed on the carriage to reciprocate in directions orthogonal to the paper feeding direction, the recording heads need to reciprocate from several dozen times to 100 times or more in order to print one entire page solidly. Accordingly, the inkjet printers may require significantly longer printing time compared to other types of printers, such as laser printers employing an electrophotographic technology for use in copiers.
By contrast, in inkjet printers including recording heads having respective widths equal to or greater than a width of a printing sheet and including no carriage (generally called “line-head printers”), have recording heads that need not reciprocate in width directions of the printing sheet. That is, the line-head printers may be able to carry out one-scanning (one-path) printing to achieve high-speed printing similar to that achieved by laser printers. In addition, since the line-head printers need not have the carriage on which the recording heads are attached, enclosures of the printers may be reduced in size and weight. Further, since the line-head printers need not have a drive device for moving the carriage with the recording heads, the printers may significantly become quieter.
When a recording element for recording an image or the like malfunctions and thus is not able to perform normal recording in the line-head inkjet printer, a recorded image may have a missing part due to the malfunction of the recording element not recording the part of the recorded image. Thus, this results in a defect of the recorded image. The cause of the malfunctioning recording element may depend largely on failure to eject ink due to nozzle clogging or ink sticking to an ink-ejecting surface resulting from the breakage of a heater in the inkjet system utilizing an electrothermal energy converter generating air bubbles in the ink to eject the ink. In order to solve the above difficulty, Japanese Patent No. 4027204 (hereinafter referred to as “Patent Document 1”) suggests that the defected recording element having a defect is replaced with another normal recording element to carry out recording in place of the defected recording element.
For example, Patent Document 1 discloses a technology for recording an image while retaining lightness by utilizing a recording element ejecting ink darker than ink ejected by a malfunctioning recording element while reducing the number of recording dots. Japanese Laid-open Patent Publication No. 2006-173929 (hereinafter referred to as “Patent Document 2”) and Japanese Laid-open Patent Publication No. 2006-212793 (hereinafter referred to as “Patent Document 3”) disclose technologies for allowing unrecorded pixels due to the malfunctioning ejection of ink to diffuse in pixels peripheral to the unrecorded pixels by detecting the unrecorded pixels and transmitting the unrecorded pixels to the peripheral pixels as errors.